Radio circuit



March 7, 1933. f R ERFEL 1,900,629

RADIO CIRCUIT Filed Oct. 19, 1932 2-Sheets-Sheet 1 'ron BY V A r O 3 ATI'ORNE INVE March 7, 1933. R. P. WUERFEL 1,900,629

RADIO CIRCUIT Filed Oct. 19, 1952 2 Sheets-Sheet 2 VENTOR ATI'OR EY Patented Mar. 7, 1933 UNITED STATES PA E T-110 F E Application fled October 1a, 1982. Serial no. seam. I

This invention relates in general to improvementsin radio circuits and particularly to the power sup ly for the filaments and plates of vacuum tubes employed in such cir- 5 cuits.

The prime object of this invention is the provision of a multi-stage vacuum tube radio circuit adapted to be energized by either direct or alternating current.

A further object of this invention is the provision of a radio circuit of this type in which the filaments or heating electrodes of the vacuum tubes are supplied directly with alternating or direct cu rrent or through a resistance. v 1 v A still further object of this invention is the provision of a circuit of this type in which all of the filaments are connected in series and energized directly from a. direct or alternating current power circuit.

A still further object of this invention involves a radio circuit employing a plurality of multi-electrode vacuum tubes in'combination with a vacuum tube rectifier so arranged and connected that the plate voltages for all the vacuum tubes may be applied from either a direct or alternating current power circuit.

These and other objects as will appear from the following disclosure are secured by means of this invention.

This invention .resides substantially in the combination, construction, arrangement, relative location of parts and circuital connections all as will be described in detail below.

Referring to the drawings,

Fig. 1 shows the invention embodied in a stem employing indirectly heated tubes in t e output stages;

Fig. 2 shows the invention embodied in a 40 system employing filamentary tubes in the output circuit; f

It is the most general practice at the present time in supplying energy for the cathodes and anodes of multi-electrode vacuum tubes and radio circuits from a power circuit such as a house lighting circuit of 110 volts. -At the resent time the apparatus employed is usua y called the power pack which must be designed for use on direct or alternating current power circuits but which is not designed for use on both. It is the general purpose of this invention to provide circuit connections and rec'tifiers which will'permit ofthe use of direct or alternating current with-' out necessitating any changes in the appara 5' tus. For example, an alternating current power pack of the type now used cannot be employed in connection with the direct current source because of the use of transformers through which a steady current, of course, cannot act. In order to fully understand this invention reference will now be made to the drawings.

Although a circuit has been shown in. the drawings employing three stages of radio frequency amplification, a detector and two stages of audio frequency amplification it will, of course, be apparent from the follow ingdisclosure that the principles of this -in'- ventionmay be applied to many other forms of radio circuits. In addition, although a vacuum tube rectifier system of one form has been disclosed the principles of this 'invention may be appliedto other known forms. The circuit is shown employing so calledscreen grid vacuum tubes in the radio frequency circuit indicated bythe reference nu-' merals 1, 2 and 3. It is likewise ap arent thatthree-electrode tubes could be use All ofthe vacuum tubes shown in this circuit have been disclosed as indirectly heated cathode vacuumtubes, but here again tubes could be used with the proper precautions employing the filaments as cathodes. The detector indi l cated at 4 is a three-electrode vacuum tube employing an indirectly heated cathode, as are the two audio amplifier tubes 5 and 6. Similar vacuum tubes 7 and .8 are used in. the rectifier. The input for the circuit is connected to the lead f vacuum tube 1 which lead is groundedto a relativelyhigh resistance as shown. The screening grids of vacuum tubes 1, 2 and 3 are shown all connected together and connected through a high resistance 21 to the positive terminal ofthe plate voltage supply. The common lead for these grids is also shown grounded through the variable resistance 22 and through a byass condenser. The indirectly heated catho e of these three tubes are all connected together and the common lead isgrounded through a resistance 23 of such value that the voltage drop through it will place the cathodes at the pro r ositive potential with respect to the gri s o the res tive tubes, this resistance being shunted y the by-pass condenser 24. The indirectly heated cathode of vacuum tube4 is connected to the negative lead of the heater element and grounded as shown at 25. All of these tubes are connected together in the usual manner by radio frequency transformers which have their secondaries tuned by a variable condenser. The indirectly heated cathodes of the vacuum tubes 5 and 6 are grounded through resistances of such value that the'voltage drop will produce the proper positive potential on the cathodes with respect to their respective grids. The terminals 30'are supplied to which the output of the last audio stage is connected to the sound reproducin device. Since vacuum tubes 7 and 8 have 0th grids and plates indicated at 10 and 11 respectively, they have been interconnected and connected to a common lead 12 which is the positive lead and which is connected to a'suitable connector 53 by which connection is made to the power source. The

' filaments or heaters of all the vacuum tubes are shown connected in series. and to wire 12 through the resistance 14. This resistance 14 is of a relatively low value and,'o course, is

proportioned so as to supply the proper voltage to the filaments of all the vacuum tubes and its size will, of course, depend upon the voltage of the power source and the number of filaments or heaters connected in series. The plate electrodes of vacuum tubes 1, 2, 3, 5 and 6 are all connected together by a common lead 19 which, in turn is connected by wire 17 to a suitable point in the filter system comprising the resistance 16, chokecoil 26 and condensers 15. Of course any suitable arrangement of resistance, inductance and capaclty may be employed in the filter. The

late electrode of vacuum tube 4 is connected y wlre 18 to the filter at a point where the proper voltage is supplied thereto. The return connection for the filaments is through wire 20 to the filter as shown. One input terminal of the filter is connected by a wire to the connector 13 which is the negative side of the line. The other input termlnalof the filter is connected by a wire 27 to both of the cathodes of the vacuum tubes 7 and 8.

The operation of this circuit with either alternating or direct current isat once ap- With either alternating or direct current supplied through connector 13 all" of the heaters or filaments of all of the vacparent.

uum tubes are energized through the properlfi porportioned resistance 14. The current W1 flow through wire 12, resistance 14, through the heaters or filaments of vacuum tubes 8 and 7 respectively, through the heaters or filaments of vacuum tubes 3, 2 and 1 respectively, through the heaters or filaments of vacuum tubes 6, 5 and 4 respectively, and

thence back through wire 20 and the filter I to the negative side of the connector. When, alternating current is used to heat the cat, h

irectly heated cathode is of course better than a directly heated cathode since a odes an in it is easier to eliminate any hum or disturb- I late current for the various tubes is all of the tubes except tube 4. For tube 4 the plate is su plied through the-filter and wire 18. The lament return lead for all of the plate circuits is through wire 20 and the filter .back tothe connector. When direct current is em loyed the output of the filter is substantia y a steady current while the pulsating current delivered by the rectifier when alternating current is used is further smoothed out by the filter.

. With proper precautions the invention may be embodied in a system employing direct 1y heated filamentary tubes in\the output circuit. Such a system is shown in Fig. 2, wherein there is employed a radio frequency amplifier tube 31 comprising an electron emitting cathode 32 which'is insulatingly spaced from its heater 33. The signals are impressed by means of the tuned input transformer 34 across the control grid 35 and the cathode 32. A suitable grid biasing resistance 36 bein provided. The screen grid 37 is connecte through a suitable resistance 38 to a positive terminal of the rectified current and is shunted by a condenser 39 in the usual manner. The tube 40 is an ordinary three-element tube of the indirectly heated cathode type, wherein the cathode 41 is ins'ulatingly spaced from the heater 42. A suitable grid bias 43 is provided for enabling the tube 42 to act properly as a detector, the signals being impressed uplon this detector from the output of tube 31 t rough the tuned coupling circuit in accordance with standard practice. The detected output is fed, by means of audio frequenc transformer 44 across the control grid 45 an the cathode'46 of a first stage amplify- .ing tube 47. Here again thecathode 46 is ins llsatingly spaced from the associated heat- 61 H The output of the amplifier 47 is impressed across a pair of output tubes 49 and 50. These tubes may be of the ordinary directly heated filamentary cathode type, these cathodes being indicated by the numerals 51 and 52.

The con lin transformer 53 is provided with a pair o in ependent secondary windings 54 ment '52. The output is taken off from the two anodes 59 and 60 by means of a coupling coil 61 in accordance with the principles ofso-called class B amplification. The operating voltages for the various anodes are derived from a suitable supply such as commercial current supply mains either of the A. C. or D. C. type. The lower main 62 is connected to the anode 63 of a vacuum tube rectifier 64. This rectifier as'shown is of the indirectly heated cathode type, wherein the cathode 65 is insulatingly spaced from its heater 66. The other main 63 is connected in. series through the filaments 52, 51, 48, 42, 33 and 66, and thence through the limiting resistance'67. Thus the said filaments are energized directly by alternating current. The potentials that areapplied to the vari- Tous anodes are derived from the rectified current passing between the anode 63 and the cathode 65. The ripples in this current being smoothed out by a suitable filter network as shown. The manner of functioning of the system of Fig. 2 is substantially the same as that of Fig. 1, and is capable of use with either direct or alternating current supplies.

From the foregoing disclosure it will be apparent that I have devised radio circuits employing tubes which can be energized .by either direct or alternating current in accordance with certain principles of constructionand operation. Those sln'lled in the art will readily appreciate that these principles of. construction and operation may be embodied in various forms of practical circuits without departing from the spirit and scope of this invention, and I do not, therefore, desire to be limited to the disclosure as given for purposes of illustration, but rather to the scope of the appended claims. 7

This application is a continuation in part of abandoned application Serial No. 398,601. 7

What is claimed is: 1. In a radio circuit of the type described, the combination comprising a plurality of coupled .multi-electrode vacuum tubes in-- cluding indirectly heated cathodes and anodes, said cathddes being provided with heater means insulatingly spaced therefrom, a rectifier having a heatable filament and an anode, a circuit including all of said heater means and. said filament adapted to be energized by direct or alternating current; a filter connected in the output of said rectifier, and

connections from the filter and theanodes of said vacuum tubes whereby a substantially constant potential is supplied thereto either from a direct or alternating current source.

. 2. In a radio circuit of the type described,

the combination comprising a plurality of coupled multi-electrode vacuum tubes including indirectly heated cathodes and anodes, said cathodes being provided with heater means insulatinglyspaced therefrom, a rectifier having a heatable filament, a circuit including a resistance, all of said heater means and said filament adapted to be enerplifier, said vacuum tubes having indirectly heated cathodes and anodes, said cathodes being provided with heater means insulatingly spaced therefrom, a thermionic rectifier likewise having a heater clement and an anode, a circuit between all of said-heaters including a resistance whereby they may be directly connected to either a direct or alternating current house lighting circuit, a filter system connected in the output of said thermionic rectifier and connections between said filter and all of the plate electrodes of said multi-electrode vacuum tubes whereby a substantially steady potential may be impressed thereon when the rectifier is ener gized by .either direct or alternating current.

4. In a radio circuit of the t e described, comprising a combined radio requency amplifier, detector and audio frequency amplifier employing a plurality of multi-electrode vacuum tubes coupled together, each of said tubes having at leastan indirectly heated cathode and an anode, said cathode being provided with heater means insulatingly spaced therefrom, a thermionic rectifier having aheatable cathode and an anode, all of current may-be directly impressed. thereon.

5. Inaradio circuit of the type described,-

the combination comprising a plurality of vacuum tubes c'ou-pled-together..to.-.form a combined detector and amplifier, indirectly heated cathodes in all of said vacuum tubes,

heaters for said cathodes, insulatingly spaced therefrom, anodes in all of said vacuum tubes,

a thermionic rectifier having cathodes and anodes, connections includin all of said heaters and the cathodes in said rectifier in-' cluding'a resistance whereby alternatingcurrent or direct current may be directly supplied thereto, a filter system in the output of said rectifier, connections between all of the anodes of said multi-electrode vacuum tubes and said filter, and connections for the anodes filter and connections for-the anode of I said rectifienwhereby either direct or alternating current may be supplied directl thereto. a

In testimon whereof Ihave hereunto set my hand on t is 13th day of October D.,

ROBERT P. WUERFEL.

of said rectifier whereby either direct or alternating current may be supplied directly thereto.

6. In a radio circuit of the type described,

the combination comprising a plurality of vacuum tubes coupled together to form a combined detector and amplifier, indirectly heated cathodes in allof said vacuum tubes,

heaters for said cathodes, anodes in all of said vacuum tubes, 2. thermionic rectifier having' indirectly heated cathodes, heaters for said cathodes and anodes, connections including all of said heaters including a resistance whereby alternating current or direct current may be directly supplied thereto, a filter system in the output of said rectifier, connectionsbetween all of the anodes of said multi-electrode vacuum tubes and said filter,

and connections for the anodes of said rectifier whereby either direct or alternating curcurrent may be directly supplied said circuit,

a filter system in the output of said rectifier cuit, a filter system conn connections between all of the anodes of sai multi-electrode vacuum tubes and said filter, and connections for the anode of said rectifier whereby either direct or alternating current may be supplied, directly thereto.

8. In a radio circuit of the type described the combination comprising a plurality of vacuum tubes coupled together to form a combined detector and amplifier, indirectly heated cathodes in all of said vacuum tubes heaters for said cathodes, anodes in all of said vacuum tubes, a thermionic rectifier having an indirectly heated cathode and an anode, heaters for all said cathodes, and a heater for said rectifier cathode, a circuit in.- cluding all of said heaters and a resistance,

means whereby alternating current or direct current may be directly sup lied to said cirto all said rectifiers, connections between all of the anodes of said multi-electrodes vacuum tubes and DISCLAIMER '1,900,629.-Rob ert P. Wuci'gl, Ann Arbor, Mich. RADIO cmcm; Patent datd March 7., 1933 Corporation of Amenca. Hereby enters this disclaimer to claims 1,to 8 inclusgve, in said specification; {Ojicial Gazette 1111191481529, 1.944; y l

Isclaim'er filed August 8, 1944, by the'assignee, Radio I 

